Commit 2451f7fc authored by catch's avatar catch

Issue #1323120 by pounard, aspilicious, beejeebus: Convert cache system to PSR-0.

parent 8a87e13a
<?php
/**
* @file
* Definition of CacheBackendInterface.
*/
namespace Drupal\Cache;
/**
* Defines an interface for cache implementations.
*
* All cache implementations have to implement this interface.
* DrupalDatabaseCache provides the default implementation, which can be
* consulted as an example.
*
* To make Drupal use your implementation for a certain cache bin, you have to
* set a variable with the name of the cache bin as its key and the name of
* your class as its value. For example, if your implementation of
* DrupalCacheInterface was called MyCustomCache, the following line would make
* Drupal use it for the 'cache_page' bin:
* @code
* variable_set('cache_class_cache_page', 'MyCustomCache');
* @endcode
*
* Additionally, you can register your cache implementation to be used by
* default for all cache bins by setting the variable 'cache_default_class' to
* the name of your implementation of the DrupalCacheInterface, e.g.
* @code
* variable_set('cache_default_class', 'MyCustomCache');
* @endcode
*
* To implement a completely custom cache bin, use the same variable format:
* @code
* variable_set('cache_class_custom_bin', 'MyCustomCache');
* @endcode
* To access your custom cache bin, specify the name of the bin when storing
* or retrieving cached data:
* @code
* cache_set($cid, $data, 'custom_bin', $expire);
* cache_get($cid, 'custom_bin');
* @endcode
*
* @see cache()
* @see DrupalDatabaseCache
*/
interface CacheBackendInterface {
/**
* Constructs a new cache backend.
*
* @param $bin
* The cache bin for which the object is created.
*/
function __construct($bin);
/**
* Returns data from the persistent cache.
*
* Data may be stored as either plain text or as serialized data. cache_get()
* will automatically return unserialized objects and arrays.
*
* @param $cid
* The cache ID of the data to retrieve.
*
* @return
* The cache or FALSE on failure.
*/
function get($cid);
/**
* Returns data from the persistent cache when given an array of cache IDs.
*
* @param $cids
* An array of cache IDs for the data to retrieve. This is passed by
* reference, and will have the IDs successfully returned from cache
* removed.
*
* @return
* An array of the items successfully returned from cache indexed by cid.
*/
function getMultiple(&$cids);
/**
* Stores data in the persistent cache.
*
* @param $cid
* The cache ID of the data to store.
* @param $data
* The data to store in the cache. Complex data types will be automatically
* serialized before insertion.
* Strings will be stored as plain text and not serialized.
* @param $expire
* One of the following values:
* - CACHE_PERMANENT: Indicates that the item should never be removed unless
* explicitly told to using cache_clear_all() with a cache ID.
* - CACHE_TEMPORARY: Indicates that the item should be removed at the next
* general cache wipe.
* - A Unix timestamp: Indicates that the item should be kept at least until
* the given time, after which it behaves like CACHE_TEMPORARY.
*/
function set($cid, $data, $expire = CACHE_PERMANENT);
/**
* Deletes an item from the cache.
*
* @param $cid
* The cache ID to delete.
*/
function delete($cid);
/**
* Deletes multiple items from the cache.
*
* @param $cids
* An array of $cids to delete.
*/
function deleteMultiple(Array $cids);
/**
* Deletes items from the cache using a wildcard prefix.
*
* @param $prefix
* A wildcard prefix.
*/
function deletePrefix($prefix);
/**
* Flushes all cache items in a bin.
*/
function flush();
/**
* Expires temporary items from the cache.
*/
function expire();
/**
* Performs garbage collection on a cache bin.
*/
function garbageCollection();
/**
* Checks if a cache bin is empty.
*
* A cache bin is considered empty if it does not contain any valid data for
* any cache ID.
*
* @return
* TRUE if the cache bin specified is empty.
*/
function isEmpty();
}
<?php
/**
* @file
* Definition of DatabaseBackend.
*/
namespace Drupal\Cache;
use Exception;
/**
* Defines a default cache implementation.
*
* This is Drupal's default cache implementation. It uses the database to store
* cached data. Each cache bin corresponds to a database table by the same name.
*/
class DatabaseBackend implements CacheBackendInterface {
/**
* @var string
*/
protected $bin;
/**
* Implements Drupal\Cache\CacheBackendInterface::__construct().
*/
function __construct($bin) {
// All cache tables should be prefixed with 'cache_', except for the
// default 'cache' bin.
if ($bin != 'cache') {
$bin = 'cache_' . $bin;
}
$this->bin = $bin;
}
/**
* Implements Drupal\Cache\CacheBackendInterface::get().
*/
function get($cid) {
$cids = array($cid);
$cache = $this->getMultiple($cids);
return reset($cache);
}
/**
* Implements Drupal\Cache\CacheBackendInterface::getMultiple().
*/
function getMultiple(&$cids) {
try {
// Garbage collection necessary when enforcing a minimum cache lifetime.
$this->garbageCollection($this->bin);
// When serving cached pages, the overhead of using db_select() was found
// to add around 30% overhead to the request. Since $this->bin is a
// variable, this means the call to db_query() here uses a concatenated
// string. This is highly discouraged under any other circumstances, and
// is used here only due to the performance overhead we would incur
// otherwise. When serving an uncached page, the overhead of using
// db_select() is a much smaller proportion of the request.
$result = db_query('SELECT cid, data, created, expire, serialized FROM {' . db_escape_table($this->bin) . '} WHERE cid IN (:cids)', array(':cids' => $cids));
$cache = array();
foreach ($result as $item) {
$item = $this->prepareItem($item);
if ($item) {
$cache[$item->cid] = $item;
}
}
$cids = array_diff($cids, array_keys($cache));
return $cache;
}
catch (Exception $e) {
// If the database is never going to be available, cache requests should
// return FALSE in order to allow exception handling to occur.
return array();
}
}
/**
* Prepares a cached item.
*
* Checks that items are either permanent or did not expire, and unserializes
* data as appropriate.
*
* @param stdClass $cache
* An item loaded from cache_get() or cache_get_multiple().
*
* @return mixed
* The item with data unserialized as appropriate or FALSE if there is no
* valid item to load.
*/
protected function prepareItem($cache) {
global $user;
if (!isset($cache->data)) {
return FALSE;
}
// If enforcing a minimum cache lifetime, validate that the data is
// currently valid for this user before we return it by making sure the cache
// entry was created before the timestamp in the current session's cache
// timer. The cache variable is loaded into the $user object by
// _drupal_session_read() in session.inc. If the data is permanent or we're
// not enforcing a minimum cache lifetime always return the cached data.
if ($cache->expire != CACHE_PERMANENT && variable_get('cache_lifetime', 0) && $user->cache > $cache->created) {
// This cache data is too old and thus not valid for us, ignore it.
return FALSE;
}
if ($cache->serialized) {
$cache->data = unserialize($cache->data);
}
return $cache;
}
/**
* Implements Drupal\Cache\CacheBackendInterface::set().
*/
function set($cid, $data, $expire = CACHE_PERMANENT) {
$fields = array(
'serialized' => 0,
'created' => REQUEST_TIME,
'expire' => $expire,
);
if (!is_string($data)) {
$fields['data'] = serialize($data);
$fields['serialized'] = 1;
}
else {
$fields['data'] = $data;
$fields['serialized'] = 0;
}
try {
db_merge($this->bin)
->key(array('cid' => $cid))
->fields($fields)
->execute();
}
catch (Exception $e) {
// The database may not be available, so we'll ignore cache_set requests.
}
}
/**
* Implements Drupal\Cache\CacheBackendInterface::delete().
*/
function delete($cid) {
db_delete($this->bin)
->condition('cid', $cid)
->execute();
}
/**
* Implements Drupal\Cache\CacheBackendInterface::deleteMultiple().
*/
function deleteMultiple(Array $cids) {
// Delete in chunks when a large array is passed.
do {
db_delete($this->bin)
->condition('cid', array_splice($cids, 0, 1000), 'IN')
->execute();
}
while (count($cids));
}
/**
* Implements Drupal\Cache\CacheBackendInterface::deletePrefix().
*/
function deletePrefix($prefix) {
db_delete($this->bin)
->condition('cid', db_like($prefix) . '%', 'LIKE')
->execute();
}
/**
* Implements Drupal\Cache\CacheBackendInterface::flush().
*/
function flush() {
db_truncate($this->bin)->execute();
}
/**
* Implements Drupal\Cache\CacheBackendInterface::expire().
*/
function expire() {
if (variable_get('cache_lifetime', 0)) {
// We store the time in the current user's $user->cache variable which
// will be saved into the sessions bin by _drupal_session_write(). We then
// simulate that the cache was flushed for this user by not returning
// cached data that was cached before the timestamp.
$GLOBALS['user']->cache = REQUEST_TIME;
$cache_flush = variable_get('cache_flush_' . $this->bin, 0);
if ($cache_flush == 0) {
// This is the first request to clear the cache, start a timer.
variable_set('cache_flush_' . $this->bin, REQUEST_TIME);
}
elseif (REQUEST_TIME > ($cache_flush + variable_get('cache_lifetime', 0))) {
// Clear the cache for everyone; cache_lifetime seconds have passed
// since the first request to clear the cache.
db_delete($this->bin)
->condition('expire', CACHE_PERMANENT, '<>')
->condition('expire', REQUEST_TIME, '<')
->execute();
variable_set('cache_flush_' . $this->bin, 0);
}
}
else {
// No minimum cache lifetime, flush all temporary cache entries now.
db_delete($this->bin)
->condition('expire', CACHE_PERMANENT, '<>')
->condition('expire', REQUEST_TIME, '<')
->execute();
}
}
/**
* Implements Drupal\Cache\CacheBackendInterface::garbageCollection().
*/
function garbageCollection() {
global $user;
// When cache lifetime is in force, avoid running garbage collection too
// often since this will remove temporary cache items indiscriminately.
$cache_flush = variable_get('cache_flush_' . $this->bin, 0);
if ($cache_flush && ($cache_flush + variable_get('cache_lifetime', 0) <= REQUEST_TIME)) {
// Reset the variable immediately to prevent a meltdown in heavy load situations.
variable_set('cache_flush_' . $this->bin, 0);
// Time to flush old cache data
db_delete($this->bin)
->condition('expire', CACHE_PERMANENT, '<>')
->condition('expire', $cache_flush, '<=')
->execute();
}
}
/**
* Implements Drupal\Cache\CacheBackendInterface::isEmpty().
*/
function isEmpty() {
$this->garbageCollection();
$query = db_select($this->bin);
$query->addExpression('1');
$result = $query->range(0, 1)
->execute()
->fetchField();
return empty($result);
}
}
<?php
/**
* @file
* Definition of InstallBackend.
*/
namespace Drupal\Cache;
use Exception;
/**
* Defines a stub cache implementation to be used during installation.
*
* The stub implementation is needed when database access is not yet available.
* Because Drupal's caching system never requires that cached data be present,
* these stub functions can short-circuit the process and sidestep the need for
* any persistent storage. Obviously, using this cache implementation during
* normal operations would have a negative impact on performance.
*
* If there is a database cache, this backend will attempt to clear it whenever
* possible. The reason for doing this is that the database cache can accumulate
* data during installation due to any full bootstraps that may occur at the
* same time (for example, Ajax requests triggered by the installer). If we
* didn't try to clear it whenever one of the delete function are called, the
* data in the cache would become stale; for example, the installer sometimes
* calls variable_set(), which updates the {variable} table and then clears the
* cache to make sure that the next page request picks up the new value.
* Not actually clearing the cache here therefore leads old variables to be
* loaded on the first page requests after installation, which can cause
* subtle bugs, some of which would not be fixed unless the site
* administrator cleared the cache manually.
*/
class InstallBackend extends DatabaseBackend {
/**
* Overrides Drupal\Cache\DatabaseBackend::get().
*/
function get($cid) {
return FALSE;
}
/**
* Overrides Drupal\Cache\DatabaseBackend::getMultiple().
*/
function getMultiple(&$cids) {
return array();
}
/**
* Overrides Drupal\Cache\DatabaseBackend::set().
*/
function set($cid, $data, $expire = CACHE_PERMANENT) {}
/**
* Implements Drupal\Cache\DatabaseBackend::delete().
*/
function delete($cid) {
try {
if (class_exists('Database')) {
parent::delete($cid);
}
}
catch (Exception $e) {}
}
/**
* Implements Drupal\Cache\DatabaseBackend::deleteMultiple().
*/
function deleteMultiple(array $cids) {
try {
if (class_exists('Database')) {
parent::deleteMultiple($cids);
}
}
catch (Exception $e) {}
}
/**
* Implements Drupal\Cache\DatabaseBackend::deletePrefix().
*/
function deletePrefix($prefix) {
try {
if (class_exists('Database')) {
parent::deletePrefix($prefix);
}
}
catch (Exception $e) {}
}
/**
* Implements Drupal\Cache\DatabaseBackend::flush().
*/
function flush() {
try {
if (class_exists('Database')) {
parent::flush();
}
}
catch (Exception $e) {}
}
/**
* Overrides Drupal\Cache\DatabaseBackend::isEmpty().
*/
function isEmpty() {
return TRUE;
}
}
<?php
/**
* @file
* Definition of NullBackend.
*/
namespace Drupal\Cache;
/**
* Defines a stub cache implementation.
*
* The stub implementation is needed when database access is not yet available.
* Because Drupal's caching system never requires that cached data be present,
* these stub functions can short-circuit the process and sidestep the need for
* any persistent storage. Using this cache implementation during normal
* operations would have a negative impact on performance.
*
* This also can be used for testing purposes.
*/
class NullBackend implements CacheBackendInterface {
/**
* Implements Drupal\Cache\CacheBackendInterface::__construct().
*/
function __construct($bin) {}
/**
* Implements Drupal\Cache\CacheBackendInterface::get().
*/
function get($cid) {
return FALSE;
}
/**
* Implements Drupal\Cache\CacheBackendInterface::getMultiple().
*/
function getMultiple(&$cids) {
return array();
}
/**
* Implements Drupal\Cache\CacheBackendInterface::set().
*/
function set($cid, $data, $expire = CACHE_PERMANENT) {}
/**
* Implements Drupal\Cache\CacheBackendInterface::delete().
*/
function delete($cid) {}
/**
* Implements Drupal\Cache\CacheBackendInterface::deleteMultiple().
*/
function deleteMultiple(array $cids) {}
/**
* Implements Drupal\Cache\CacheBackendInterface::deletePrefix().
*/
function deletePrefix($prefix) {}
/**
* Implements Drupal\Cache\CacheBackendInterface::flush().
*/
function flush() {}
/**
* Implements Drupal\Cache\CacheBackendInterface::expire().
*/
function expire() {}
/**
* Implements Drupal\Cache\CacheBackendInterface::garbageCollection().
*/
function garbageCollection() {}
/**
* Implements Drupal\Cache\CacheBackendInterface::isEmpty().
*/
function isEmpty() {
return TRUE;
}
}
<?php
/**
* @file
* Provides a stub cache implementation to be used during installation.
*/
/**
* Defines a stub cache implementation to be used during installation.
*
* The stub implementation is needed when database access is not yet available.
* Because Drupal's caching system never requires that cached data be present,
* these stub functions can short-circuit the process and sidestep the need for
* any persistent storage. Obviously, using this cache implementation during
* normal operations would have a negative impact on performance.
*/
class DrupalFakeCache extends DrupalDatabaseCache implements DrupalCacheInterface {
/**
* Overrides DrupalDatabaseCache::get().
*/
function get($cid) {
return FALSE;
}
/**
* Overrides DrupalDatabaseCache::getMultiple().
*/
function getMultiple(&$cids) {
return array();
}
/**
* Overrides DrupalDatabaseCache::set().
*/
function set($cid, $data, $expire = CACHE_PERMANENT) {
}
/**
* Implements DrupalCacheInterface::deletePrefix().
*/
function deletePrefix($cid) {
try {
if (class_exists('Database')) {
parent::deletePrefix($cid);
}
}
catch (Exception $e) {
}
}
/**
* Overrides DrupalDatabaseCache::clear().
*/
function clear($cid = NULL, $wildcard = FALSE) {
// If there is a database cache, attempt to clear it whenever possible. The
// reason for doing this is that the database cache can accumulate data
// during installation due to any full bootstraps that may occur at the
// same time (for example, Ajax requests triggered by the installer). If we
// didn't try to clear it whenever this function is called, the data in the
// cache would become stale; for example, the installer sometimes calls
// variable_set(), which updates the {variable} table and then clears the
// cache to make sure that the next page request picks up the new value.
// Not actually clearing the cache here therefore leads old variables to be
// loaded on the first page requests after installation, which can cause
// subtle bugs, some of which would not be fixed unless the site
// administrator cleared the cache manually.
try {
if (class_exists('Database')) {
parent::clear($cid, $wildcard);
}
}
// If the attempt at clearing the cache causes an error, that means that
// either the database connection is not set up yet or the relevant cache
// table in the database has not yet been created, so we can safely do
// nothing here.
catch (Exception $e) {
}
}
/**
* Overrides DrupalDatabaseCache::isEmpty().
*/
function isEmpty() {
return TRUE;
}
}
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......@@ -277,8 +277,7 @@ function install_begin_request(&$install_state) {